1. Field of the Invention
The present invention relates to a secondary battery, and more particularly to a secondary battery having a resin cavity side covering.
2. Description of Related Art
Secondary batteries are rechargeable batteries and are often used as a power source for various portable electronic devices, for example, cellular phones, laptop computers, camcorders, and hybrid motor vehicles.
In particular, a lithium secondary battery has an operating voltage of 3.6 volts, which is about 3 times greater than nickel-cadmium (Ni—Cd) batteries, or nickel-hydrogen (Ni-MH) batteries commonly used to power electronic equipment. In addition, since energy density per unit weight of lithium secondary batteries is high, secondary batteries can be compact. Accordingly, lithium secondary batteries are often now used instead of Ni—Cd or Ni-MH batteries.
Conventional lithium secondary batteries have a prismatic exterior made from a thin sheet of metal. Prismatic secondary batteries typically include a cover and an outer case attached to a bare cell having an electrode assembly housed in a can. The cover is often made from a resin molded cover and an injection molded hard cover. When a circuit module, such as a protective circuit, is attached to the bare cell to form a core pack, the resin molding cover at least partially covers the circuit module. When the hard cover is attached to the resin molding cover, part of the hard cover is overlapped by the resin cover. Usually, such a configuration is used on secondary batteries, such as prismatic secondary batteries, which do not have an external electrode terminal. In such a configuration, the side cover is relatively weakly attached to the can, causing frequent separation between the side cover and the can.
To reinforce the weak adhesion, a label may be used to cover the side cover. However, if the label is damaged, the attachment between the side cover and the can may deteriorate or fail. Moreover, since insulation and mechanical protection of the secondary battery is dependent on the side cover, if the boundary between the side cover and the rest of the secondary battery degrades, a gap is created between the side cover and the can, allowing debris such as dust or humidity to infiltrate the gap, thereby degrading the quality of the secondary battery.